Cooling system for a combustion engine, combustion engine and motor vehicle with a combustion engine

ABSTRACT

A cooling system is provided for a combustion engine having at least one pressure sensor and a diaphragm. The diaphragm is impermeable to a coolant of the cooling system and in contact with the coolant on a first side. A sensor device of the at least one pressure sensor is arranged separated from the coolant on a second side of the diaphragm located opposite the first side and configured to determine a pressure of the coolant.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No.102010048859.3, filed Oct. 19, 2010, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The technical field relates to a cooling system for a combustion engine,a combustion engine with a cooling system and a motor vehicle with acombustion engine.

BACKGROUND

From U.S. Pat. No. 5,184,514 a pressure insulating device having a bodyof a first metallic material is known. The pressure insulating deviceadditionally comprises a thin flexible diaphragm of a second metallicmaterial, which cannot be connected to the first metallic materialthrough direct welding. Furthermore, the pressure insulating devicecomprises a support ring of the same material as the diaphragm, which ismounted on the body, which surrounds an insulating opening. In additionto this, the pressure insulating device comprises a ring-shaped weldring which is produced from the same material as the diaphragm and lieson a circumferential edge of the diaphragm and of the support ring andcomprises a ring-shaped circumferential weld seam.

The circumferential weld seam runs through the weld ring, in order toseal and interconnect the support ring, the diaphragm and the weld ringabout the circumference of the diaphragm, in order to create a sealedhollow space relative to the body and to the insulating opening. Theweld ring forms a ring-shaped hollow space that lies on the diaphragmand comprises a basic wall through which the weld seam runs, and walls,which extend from the basic wall that defines a ring-shaped recess inorder to receive a ring-shaped compressible seal for a process fluidconnection.

In view of the foregoing, at least one object is to state a coolingsystem for a combustion engine, a combustion engine with a coolingsystem and a motor vehicle with a combustion engine, which make possibleimproved control or diagnosis possibilities of the cooling system in asimple manner. In addition, other objects, desirable features andcharacteristics will become apparent from the subsequent summary anddetailed description, and the appended claims, taken in conjunction withthe accompanying drawings and this background.

SUMMARY

According to an embodiment, the cooling system for a combustion enginecomprises a pressure sensor and a diaphragm. The diaphragm isimpermeable to a coolant of the cooling system. Furthermore, thediaphragm is in contact with the coolant on a first side. A sensordevice of the at least one pressure sensor is arranged separated fromthe coolant on a second side of the diaphragm located opposite the firstside and designed for determining a pressure of the coolant.

The cooling system makes possible the provision of improved control ordiagnosis possibilities through the provision of at least one pressuresensor. The application starts out from the consideration that theknowledge of the pressure of the coolant on the one hand providesexpanded possibilities for the temperature control of the coolingsystem. Furthermore, the knowledge of the pressure of the coolant or atemporal course of the pressure of the coolant makes possible expandeddiagnostic functions for the cooling system. In this respect, thecooling system has the advantage that through the provision of thediaphragm that is impermeable the coolant and the arrangement of thesensor device in such a manner that it is separated from the coolant,pressure sensors can be employed in the cooling system whose sensordevices are not intended for the use in such a hot and wet environment.

As a result, cost-effective pressure sensors or sensor devices for thecooling system can be used in particular, which are already employed inadditional components of the combustion engine. For example, a sensorthat is employed in intake lines of the combustion engine or in chargepressure lines with a charged combustion engine, i.e. in substantiallydry, gaseous environments, can be used as pressure sensor for thecooling system. Compared with other pressure sensors, thisadvantageously leads to a reduction of the development costs ordevelopment and validation time. In addition, fewer differentreplacement parts for the combustion engine have to be kept in stock.

In an embodiment the diaphragm comprises a material with a meltingtemperature T_(S,M), where T_(S,M)>approximately 150° C. and preferablyT_(S,M)>approximately 200° C. In this respect, the melting temperatureis based on the normal pressure. Based on the generally merely lowpressure dependency of the melting temperature the mentioned value issubstantially unchanged for the further pressure values that typicallyprevail in the cooling system. In this respect the material can comprisetantalum or a tantalum alloy or hydrogenated acrylonitrile butadienerubber (HNBR). The mentioned embodiments have the advantage that thediaphragm is designed particularly heat-resistant because of this.

In a further embodiment, the sensor device comprises a semi-conductorpressure sensor chip. Such sensor chips are more preferably used in themotor vehicle sector and thus have the advantage that they cover themeasuring ranges that are typical for such applications. Preferably, theat least one pressure sensor additionally comprises a housing with anopening. The sensor device is arranged in the opening of the housing andthe diaphragm covers the opening. This makes possible a particularlysimple arrangement of the diaphragm on the pressure sensor.

In a further embodiment the housing in this respect comprises a materialwith a melting temperature T_(S,G), where T_(S,G)>approximately 150° C.and further preferably T_(S,G)>approximately 200° C. In this respect,especially those regions of the housing that are in contact with thecoolant preferably includes such a material. Because of this, thehousing is advantageously adapted to the high ambient temperatures.

The material is preferably selected from the group consisting ofpolyphenylene sulfide and polybutylene terephtalate. The two mentionedsubstances form high-temperature resistant thermoplastics and because ofthis are particularly suited as housing material, even with a continuoususe under high temperatures. In addition, the mentioned substancesadvantageously comprise a high chemical resistance and are thusparticularly suited for a long-term use.

The diaphragm can be connected to the housing by means of an adhesive.This makes possible a simple fastening of the diaphragm to the housing.As suitable materials, the adhesive comprises for example fluorosiliconeresin or fluoride resin. In a further embodiment, the diaphragm isconnected to the housing by means of a screw connection. Preferably anO-ring seal is provided between the diaphragm and the housing.Furthermore, upon suitable material selection of the diaphragm and ofthe housing, the diaphragm can be connected to the housing by means of asoldering or welding connection.

Here, in a further embodiment a fluid is arranged between the diaphragmand the sensor device. A pressure exerted by the coolant on the firstside of the diaphragm is transmitted to the sensor device by means ofthe fluid. Here, the fluid is preferably a gas, wherein the gas is forexample formed through the ambient air. Because of this, sensor devicesin turn can be advantageously provided for the at least one pressuresensor, which are provided for a use in a gas atmosphere.

In a preferred embodiment a characteristic curve of the sensor device iscorrected for pressure dampening effects of the diaphragm. Typically,this is affected in that a pressure reduction caused by the diaphragm isincorporated in the characteristic curve. Such pressure dampeningeffects of the diaphragm in this respect are preferably determined evenbefore an installation of the pressure sensor in the cooling system andthe characteristic curve suitably corrected. Because of this, the actualpressure of the coolant can be advantageously determined as accuratelyas possible. The characteristic curve of the sensor device in thisrespect can for example be stored in a storage device that is part of anengine control device of the combustion engine.

In an embodiment, the at least one pressure sensor is arranged in anexpansion tank of the cooling system. Because of this, the installationexpenditure for the pressure sensor is advantageously very low. In afurther embodiment the at least one pressure sensor is arranged on anoutput side of a coolant pump of the cooling system. Preferably, the atleast one pressure sensor in this respect is arranged on an exhaust sideof the combustion engine. The at least one pressure sensor is thusarranged on a high-pressure side of the coolant pump of the coolingsystem. This has the advantage that the pressure of the coolant can bedetermined on the outlet side of the coolant pump, as a result of whichfurther control possibilities for the cooling system can be provided. Tothis end, the coolant pump can be preferably actuated by a controldevice, wherein the control device is in operational connection with theat least one pressure sensor.

A combustion engine is also provided that has a cooling system accordingto any one of the mentioned embodiments. The combustion engine in thisrespect is typically designed as liquid-cooled combustion engine.Furthermore, the application relates to a motor vehicle having acombustion engine according to the mentioned embodiments. In thisrespect, the motor vehicle is typically a passenger car or a commercialvehicle. The combustion engine and the motor vehicle according to theapplication have the advantages already mentioned in connection with thecooling system according to the application, which are not stated againat this point to avoid repetitions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and:

FIG. 1 shows a motor vehicle with a combustion engine according to theembodiment;

FIG. 2 shows a cooling system according to a first embodiment for thecombustion engine according to FIG. 1;

FIG. 3 shows a cooling system according to a second embodiment for thecombustion engine according to FIG. 1; and

FIG. 4 shows the pressure sensor of the cooling systems according toFIG. 2 and FIG. 3.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit application and uses. Furthermore, there is nointention to be bound by any theory presented in the precedingbackground or summary or the following detailed description.

FIG. 1 shows a motor vehicle 15 with a combustion engine 2 according toan embodiment. The motor vehicle 15 in the shown embodiment is apassenger car and the combustion engine 2 is designed as liquid-cooledcombustion engine. Further details are explained in more detail inconnection with the following figures. To this end, FIG. 2 shows acooling system 1 according to a first embodiment of the application forthe combustion engine 2 according to FIG. 1.

The combustion engine 2 comprises an inlet side 37 and an exhaust side38. On the exhaust side 38 of the combustion engine 2 a branch-off 19 isarranged, from which a coolant line 23 leads to a coolant radiator 18.From the coolant radiator 18 a further coolant line 24 leads to athermostat valve 20 arranged on the inlet side 37. Here, the thermostatvalve 20 in the embodiment shown comprises an expansion material element21 for example containing wax, wherein by means of the expansionmaterial element 21 an opening temperature of the thermostat valve 20 isdetermined In flow direction of a coolant of the cooling system 1 notshown in more detail behind the thermostat valve 20 a coolant line 39leads to a coolant pump 12.

From the branch-off 19 a coolant line 22 additionally leads to a heaterheat exchanger 17. From the heater heat exchanger 17 in turn a coolantline 25 leads to the inlet side 37. The coolant line 25 in this respectbranches off into a coolant line 26 and a coolant line 27. The coolantline 27 leads to an expansion tank 10 of the cooling system 1. The inletside 37 of the combustion engine 2 is additionally connected to theexhaust side 38 via a bypass channel in the form of a coolant line 28.The coolant line 28 in the shown embodiment is partly arranged in acrankcase 16 of the combustion engine 2. The region of the coolant line28 running within the crankcase 16 in this respect is represented byinterrupted lines. The coolant line 28 leads from the branch-off 19 to ajunction 40. At the junction 40, the coolant line 28 and the coolantline 26 lead into each other. A coolant line 41 leads from the junction40 to the coolant line 39.

The coolant which is not shown in more detail, coming from the inletside 37, flows through the combustion engine 2. The respective flowdirection of the coolant in this respect is shown by means of arrows inFIG. 2. In the shown embodiment, the cooling system 1 comprises apressure sensor 3 which is arranged in the expansion tank 10 of thecooling system 1. The pressure sensor 3 in this respect can be arrangedin the region of the expansion tank 10 with liquid coolant or in theregion of the gaseous coolant. Further details of the pressure sensor 3will be explained in more detail in connection with FIG. 4.

The pressure sensor 3 is connected to an evaluation device 30 via asignal line 32, which evaluation device is designed for evaluating thepressure values of the coolant determined by means of the pressuresensor 3. The evaluation device 30 in the embodiment shown is part of anengine control device 29 of the combustion engine 2.

Furthermore, the motor vehicle not shown in more detail in FIG. 2comprises an output device 31, which is designed for outputting awarning message should the pressure of the coolant drop below apredetermined threshold value. In particular, the output device 31 canbe designed for outputting a warning message if the pressure of thecoolant should drop below a threshold value within a predeterminedduration. To this end, the output device 31 is connected to the enginecontrol device 29 via a signal line 33. Typically, the output device 31is designed for outputting a visual and/or acoustic and/or hapticwarning message.

For example, a warning message can be output in the event that an abruptpressure loss of the coolant is determined Such a pressure loss canpoint to a leak in the cooling system 1, for example due to a fallen-offor burst coolant hose. By outputting the warning message the occupantsof the motor vehicle, particularly the driver of the motor vehicle, canbe timely alerted to this situation as a result of which damages to thecombustion engine 2 can be prevented. Thus, in the embodiment shown, theuse of the pressure sensor 3 in the cooling system 1 provides expandedfault diagnosis possibilities for the cooling system 1.

FIG. 3 shows a cooling system 1′ according to a second embodiment forthe combustion engine 2 according to FIG. 1. Components with the samefunctions as in the preceding figures are marked with the same referencecharacters and are not explained in more detail in the following. In theshown embodiment, the cooling system 1′ in turn comprises a pressuresensor 3, wherein the pressure sensor 3 is arranged on an outlet side 11of the coolant pump 12 of the cooling system 1′, i.e., on ahigh-pressure side of the coolant pump 12. In the embodiment shown, thepressure sensor 3 in this respect is arranged on the exhaust side 38 ofthe combustion engine 2.

The coolant pump 12, which additionally comprises an inlet side 13, canbe actuated by a control device 14. The coolant pump 12 can for examplebe designed as electric coolant pump, i.e., as coolant pump having anelectric motor driving it. Furthermore, the coolant pump 12 can bedesigned as belt-driven coolant pump having a clutch, for example amagnetic clutch, which is arranged between the coolant pump and a drivebelt that is not shown in more detail. In the first mentioned case theelectric motor and in the second mentioned case the clutch is connectedto the control device 14, as a result of which the coolant pump 12 ineach case can be switched on and off. Furthermore, an actuatable coverthat is arranged on the suction opening of the coolant pump 12 can beprovided.

In the embodiment shown, the control device 14 is part of the tensioncontrol device 29 of the combustion engine 2. In addition, the controldevice 14 is in operational connection with the pressure sensor 3. Tothis end, the pressure sensor is connected to the engine control device29 via a signal line 43. In the mentioned embodiment, the use of thepressure sensor 3 in the cooling system 1′ thus makes possible theprovision of expanded control functions of the engine control device 29for the cooling system 1′. Further details of the pressure sensor 3 areexplained in more detail in connection with the following figure.

In this respect, FIG. 4 shows the pressure sensor 3 of the coolingsystem 1 according to FIG. 2 and of the cooling system 1′ according toFIG. 3. The pressure sensor 3 comprises a sensor device 6, which isdesigned for determining a pressure of the coolant which is not shown inmore detail of the respective cooling system. The sensor device 6 inthis respect comprises a semi-conductor pressure sensor chip 44 in theshown embodiment, for example a silicon-based pressure sensor chip.

Typically, the sensor device 6 has a measuring range for an absolutepressure of up to approximately 250 kPa, preferably up to approximately300 kPa and more preferably up to approximately 400 kPa, or a measuringrange for the differential pressure between the pressure of the coolantand the ambient pressure of up to approximately 150 kPa, preferably upto approximately 200 kPa and more preferably up to approximately 300kPa.

Furthermore, the pressure sensor 3 comprises a housing 8 with an opening9. The sensor device 6 is arranged in the opening 9 of the housing 8. Adiaphragm 4 covers the opening 9. The diaphragm 4 is impermeable to thecoolant of the cooling system and is in contact with the coolant on afirst side 5. On a second side 7 of the diaphragm 4 located opposite thefirst side 5 the sensor device 6 is arranged separated from the coolantand thus advantageously protected from the rough ambient conditions inthe form of heat and moisture. The diaphragm 4 to this end comprises amaterial with a melting temperature T_(S,M), whereinT_(S,M)>approximately 150° C., wherein more preferablyT_(S,M)>approximately 200° C. applies. For example, the diaphragm 4comprises tantalum or a tantalum alloy or hydrogenated acrylonitrilebutadiene rubber (HNBR).

In the shown embodiment, the housing 8 additionally comprises a materialwith a melting temperature T_(S,G), wherein T_(S,G)>approximately 150°C., more preferably T_(S,G)>approximately 200° C. applies. For example,the housing comprises polyphenylene sulfide and polybutyleneterephtalate.

Between the diaphragm 4 and the sensor device 6 is located a fluid thatis not shown in more detail, wherein this fluid in the embodiment shownis formed through the ambient air. A pressure exerted by the coolant onthe first side 5 of the diaphragm 4 is transmitted to the sensor device6 by means of the fluid.

A bond wire 35 connects the semi-conductor pressure sensor chip 44 to aconnection line 34. Between the connection line 34 and the housing 8sealing material 36 is arranged, as a result of which the sensor device6 is protected from an entry of the coolant to a further increaseddegree.

Although at least an exemplary embodiment was shown in the precedingdescription, different changes and modifications can be carried out. Thementioned embodiments are merely examples and not intended to restrictthe scope, the applicability or the configuration in any mannerwhatsoever. On the contrary, the preceding description at least makesavailable a plan for implementing at least one exemplary embodiment tothe person skilled in the art, where numerous changes in the functionand the arrangement of elements described in an exemplary embodiment canbe made without leaving the scope of protection as set forth in thefollowing claims.

1. A cooling system for a combustion engine, comprising: a coolant; apressure sensor; a diaphragm that is impermeable to the coolant and on afirst side in contact with the coolant; and a sensor device of thepressure sensor on a second side of the diaphragm located opposite thefirst side and arranged to separate from the coolant and configured todetermine a pressure of the coolant.
 2. The cooling system according toclaim 1, wherein the diaphragm comprises a material with a meltingtemperature T_(S,M), and wherein T_(S,M)>approximately 150° C.
 3. Thecooling system according to claim 2, wherein the material comprisestantalum.
 4. The cooling system according to claim 2, wherein thematerial comprises a tantalum alloy.
 5. The cooling system according toclaim 2, wherein the material comprises a hydrogenated acrylonitrilebutadiene rubber.
 6. The cooling system according to claim 1, whereinthe sensor device comprises a semi-conductor pressure sensor chip. 7.The cooling system according to claim 1, wherein the pressure sensorfurther comprises a housing with an opening, wherein the sensor deviceis arranged in the opening of the housing, and wherein the diaphragm isconfigured to cover the opening.
 8. The cooling system according toclaim 7, wherein the housing comprises a material with a meltingtemperate T_(S,G), and wherein T_(S,G)>approximately 150° C.
 9. Thecooling system according to claim 8, wherein the material comprises apolyphenylene sulfide.
 10. The cooling system according to claim 8,wherein the material comprises a polybutylene terephtalate.
 11. Thecooling system according to claim 7, wherein the diaphragm is connectedto the housing with an adhesive.
 12. The cooling system according toclaim 1, wherein a fluid is located between the diaphragm and the sensordevice.
 13. The cooling system according to claim 1, wherein acharacteristic curve of the sensor device is corrected for pressuredampening effects of the diaphragm.
 14. The cooling system according toclaim 1, wherein the pressure sensor is arranged in an expansion tank.15. The cooling system according to claim 1, wherein the pressure sensoris arranged on an outlet side of a coolant pump.
 16. The cooling systemaccording to claim 15, wherein the coolant pump is configured to actuateby a control device, and wherein the control device is operablyconnected with the pressure sensor.